In high-output power looms, the heddle shaft is subject to a severe vibration load. This must not cause tearing of material, vibration breakage and the like at any point of the heddle shaft, including at the ends of the heddle shafts.
The design of the connection between the lateral bracing posts and the shaft rods has been the subject in the past of various attempts at optimization:
From German Patent Disclosure DE 196 12 404 A1, a heddle shaft is known that has releasable corner connections between the lateral bracing post and the shaft rod. At each corner connection, a corner connector is inserted in the applicable hollow chamber and is riveted to the side wall of the hollow chamber embodied in the shaft rod. A pinlike protrusion provided on the lateral bracing post enters into a recess of the corner connector and is secured in this recess by a clamping screw. Once the clamping screw is loosened, the lateral bracing post can be removed.
The same reference, in a further embodiment, discloses a corner connection in which the pinlike protrusion is provided with an elastic bearing part, which fits over the flat pin on its top, its face end, and its underside. The bearing part 14 is intended to damp vibration.
From German Patent DE 198 58 013 C2, a connection between a shaft rod and a lateral bracing post is known for heddle shafts with a shaft-heddle system without heddle rod hooks. The connection includes a connecting piece, introduced into the hollow chamber of the shaft rod, that has a recess for receiving a pin provided on the lateral bracing post. This pin has a plastic adaptor and with it engages the aforementioned recess. A fastening screw extending through the pin longitudinally is anchored in a threaded piece that is seated in the connecting piece that has been inserted into the hollow chamber of the shaft rod. The connecting piece has a certain movability in the hollow chamber, in the longitudinal direction of the lateral bracing post, and is braced in one direction by two compression springs. On the top, it is braced by a screw, with which the precise position of the connecting piece can be adjusted. With this provision, the heddle play can be adjusted.
At high operating speeds of the power looms, heddle shafts are accelerated and braked very sharply, so that particularly in the region of the connecting points between the lateral bracing posts and the shaft rods, major forces occur. These must not cause damage to either the lateral bracing posts or the shaft rods. For this purpose, screws penetrating the pin longitudinally, or rivets extending through the side wall of the shaft rod, have proved to be weak points. Moreover, a corner connection should be as simple as possible to make and should not require any special tools.
With this as the point of departure, it is the object of the invention to create a heddle shaft for power looms that can be installed and uninstalled quickly and simply and has a high load-bearing capacity. This object is attained with the heddle shaft of claim 1: